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cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()

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Rename cgroup_subsys css lifetime related callbacks to better describe
what their roles are.  Also, update documentation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
2012-11-19 08:13:38 -08:00
parent b1929db42f
commit 92fb97487a
13 changed files with 130 additions and 119 deletions
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35
include/linux/cgroup.h
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@@ -82,7 +82,7 @@ struct cgroup_subsys_state {
/* bits in struct cgroup_subsys_state flags field */
enum {
CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
CSS_ONLINE = (1 << 1), /* between ->post_create() and ->pre_destroy() */
CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
};
/* Caller must verify that the css is not for root cgroup */
@@ -439,10 +439,11 @@ int cgroup_taskset_size(struct cgroup_taskset *tset);
*/
struct cgroup_subsys {
struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
int (*post_create)(struct cgroup *cgrp);
void (*pre_destroy)(struct cgroup *cgrp);
void (*destroy)(struct cgroup *cgrp);
struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp);
int (*css_online)(struct cgroup *cgrp);
void (*css_offline)(struct cgroup *cgrp);
void (*css_free)(struct cgroup *cgrp);
int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
@@ -541,13 +542,13 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
* @cgroup: cgroup whose children to walk
*
* Walk @cgroup's children. Must be called under rcu_read_lock(). A child
* cgroup which hasn't finished ->post_create() or already has finished
* ->pre_destroy() may show up during traversal and it's each subsystem's
* cgroup which hasn't finished ->css_online() or already has finished
* ->css_offline() may show up during traversal and it's each subsystem's
* responsibility to verify that each @pos is alive.
*
* If a subsystem synchronizes against the parent in its ->post_create()
* and before starting iterating, a cgroup which finished ->post_create()
* is guaranteed to be visible in the future iterations.
* If a subsystem synchronizes against the parent in its ->css_online() and
* before starting iterating, a cgroup which finished ->css_online() is
* guaranteed to be visible in the future iterations.
*/
#define cgroup_for_each_child(pos, cgroup) \
list_for_each_entry_rcu(pos, &(cgroup)->children, sibling)
@@ -561,19 +562,19 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
* @cgroup: cgroup whose descendants to walk
*
* Walk @cgroup's descendants. Must be called under rcu_read_lock(). A
* descendant cgroup which hasn't finished ->post_create() or already has
* finished ->pre_destroy() may show up during traversal and it's each
* descendant cgroup which hasn't finished ->css_online() or already has
* finished ->css_offline() may show up during traversal and it's each
* subsystem's responsibility to verify that each @pos is alive.
*
* If a subsystem synchronizes against the parent in its ->post_create()
* and before starting iterating, and synchronizes against @pos on each
* iteration, any descendant cgroup which finished ->post_create() is
* If a subsystem synchronizes against the parent in its ->css_online() and
* before starting iterating, and synchronizes against @pos on each
* iteration, any descendant cgroup which finished ->css_offline() is
* guaranteed to be visible in the future iterations.
*
* In other words, the following guarantees that a descendant can't escape
* state updates of its ancestors.
*
* my_post_create(@cgrp)
* my_online(@cgrp)
* {
* Lock @cgrp->parent and @cgrp;
* Inherit state from @cgrp->parent;
@@ -606,7 +607,7 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
* iteration should lock and unlock both @pos->parent and @pos.
*
* Alternatively, a subsystem may choose to use a single global lock to
* synchronize ->post_create() and ->pre_destroy() against tree-walking
* synchronize ->css_online() and ->css_offline() against tree-walking
* operations.
*/
#define cgroup_for_each_descendant_pre(pos, cgroup) \